Non mechanical valves or filters have been widely used in suction devices for aspirating bodily fluids. These devices are generally made from sintered porous plastic comprising a water absorbable agent such as a super absorbent material to prevent bodily fluids from entering the vacuum system. Some examples of these devices are provided in WO87/00439 and U.S. Pat. Nos. 6,780,309 and 3,982,538.
These devices are generally filters employing a single part of a sintered product with uniform chemical composition, pore size and pore volume throughout the part, as in U.S. Pat. No. 6,780,309. This type of product can meet some application requirements, however it does not function well in certain applications, such as in surgeries that generate high concentrations of fumes or aerosols. The fumes often cause premature shut down of the vacuum system by clogging the filter. The premature clogging is caused by the particles or vapor in the fume generated during the surgical procedure. The filter will fail when encountering a relatively large amount of surgical fumes even though the filter has not contacted the body fluid which the filter is designed for. There is a need for a non mechanical valve that can withstand exposure to surgical fumes and aerosols and block the passage of bodily fluids.
In order to achieve good capability to block the passage of bodily fluids, sintered porous plastic non mechanical valves need to have a relatively small pore size. However, the small pore size may cause premature shut off of the vacuum suction canister when surgical fumes exist. Surgical fume contains organic particles, water, and organic vapors and aerosols generated during the surgery. These components in the surgical fume deposit on the non mechanical valve block the pores in the non mechanical valve, and cause the premature shut off of the vacuum suction canister.
Another drawback for currently available products is premature shut off when the suction during surgery generates liquid foams or bubbles. The foams or bubbles reach the non mechanical valve (filter) long before the liquid. The foams or bubbles will prematurely trigger the self-sealing action on current products and shut off the vacuum even though the liquid in the suction canister is very low.
The premature shut off of suction vacuum during surgery may have a life threatening impact, as the surgical field of view may be temporarily obscured to the surgeon. Further, such events increase the time in the operating room and increase costs. There is a need in the market for non mechanical valves that reduce premature shut off of the vacuum suction canister caused by fumes, liquid flush, foams or bubbles generated during surgery.
There is a need for a new non mechanical valve for medical suction devices that has high bulk liquid blocking capability and high bacterial aerosol filtration efficiency to prevent vacuum line contamination; and has high smoke, foam and liquid flushing tolerance to prevent premature shut-off during surgical procedures.